http://cws.gtc.edu/faculty/zambos/ChemistryNotes

 

 

Signed Numbers

 

-3 + - 8 =   - 11

 

The first sign after the first number indicates the type of problem.  This is an addition problem.   50% of the time on an addition problem, you are going to subtract.

 

How do you know when you add on an addition problem?

When both numbers have the same sign.

 

How do you know when you subtract on an addition problem?

When the numbers have opposite signs.   Subtract smaller number from the larger

 

Example:

-         4 + + 6

 

6 – 4 = 2  Is the answer positive or negative.  Attach the sign of the larger number.  Since 6 is larger than 4, then the answer is positive.

 

Answer is positive 2

 

Why is this a subtraction problem?

 -3 - + 8 =

 

Because the first sign after the first number is “-“

50% of the time you will add on a subtraction problem. 

 

Always change a subtraction problem to an addition problem.

We do this by adding the opposite.

 

So if I have  -3 - + 8 =

Change the subtraction to an addition and add the opposite

-3 + - 8 =  -11

 

 

6 – 24 =

6 - + 24 =

+ 6 + - 24 =

24 – 6 = 18 ΰ - 18

 

Shortcut  Always change a minus to a + - .

-         3 – 8 =

 

 

Given

B   Boron

 

C    Carbon

 

Be   Beryllium

 

 

Ne   Neon

 

 S    sulfur

 

P    phosphorous

 

Si   silicon

 

·        oxygen

 

Na  sodium

 

K  potassium

 

Al  aluminum

 

Cl  chlorine

 

Ar   Argon

 

He  helium

 

H  hydrogen

 

 

 

 

 

 

 

 

 

 

 

 

Quiz 1 Chemistry  First 20 elements

 

1.        C

 

2.        F

 

3.        O

 

4.        H

 

5.        Al

 

6.        Si

 

7.        He

 

8.        Na

 

9.        Li

 

10.   K

 

11.   Be

 

12.   Mg

 

13.   Ca

 

14.    P

 

15.   N

 

16.   S

 

17.   Cl

 

18.   Ne

 

19.   Ar

 

20.   B

 

Page 6 of the syllabus, we have more elements

 

Cr    Chromium

Mn   Manganese

Fe     Iron  “ferrium”  Ferrier

Precious Metal

Copper   Cu  “cuprum”

Silver      Ag   “Argentium”

Gold        Au    “ aurum”

Platinum   Pt

Zinc          Zn

Arsenic     As

Bromine    Br

Tin             Sn  “stannum”

Antimony   Sb     typically a catalyst.  A catalyst speeds up a chemical reaction, but does not take part in it.

I   iodine

Hg   Mercury

Pb    Lead

U      Uranium

Pu     Plutonium

 

 

Section 2.2 in the textbook

 

Metric System

 

There are 3 basic units

Meter    Meter is approximately 39.37 inches  (a little longer than a yard)

Liter      Is 33.7 fl. oz   Which is a liter more than a quart

 

Gram     There are 28.34 grams in an ounce.  (Its about the weight of 2 paper clips)

 

Using the meter as a unit to measure a postage stamp is inconvenient.  So the metric system uses prefixes to change units to more convenient sizes.

Prefix

Power of 10

Example

Kilo (k)

1000

A kilometer is 1000 meters  1.609 km = 1 mile

Hecto (h)

100

A hectometer is 100 meters.

Deka  (da)

10

A decameter is 10 meters

Meter (m), liter, (L)gram (g) (basic unit)

1

 

Deci  (d)

1/10 or 0.1

A decigram is 1/10 of a gram

Centi (c)

1/100   0.01

A centimeter is 1/100 of a meter.

Milli (m)

1/1000 or 0.001

A milligram is 1/1000 of a gram

Micro (mc) (΅)

1/1,000,000 or 0.000001

A microgram is 1/1,000,000 of a gram

 

 

 

 

Decade

Century

millineum

 


k  h  da  bu  d  c  m  _  _  mc

 


0.075 hm  = ____ cm

Since we move 4 places to the right on the chart, we move the decimal point 4 places to the right.

 

 

How do we remember the chart?

Kangaroos hop daily but don’t chew much

 


k  h  da  bu  d  c  m  _  _  mc

 

 


Convert  .235 Kg   = ____g

 


Convert 799 cm = ____ dam

 

k  h  da  bu  d  c  m  _  _  mc

 

 


Convert 81 m = ____ mm

 

k  h  da  bu  d  c  m  _  _  mc

 

 

 

How do you convert square feet to square yards.

WhatWwW

 

What is the area?   A = LW  = (3 ft)(3 ft) = 9 ft2.

What is the area?   A = LW  = (1 yd)(1 yd) = 1 yd2

Areas measure surface.  (units)2.

Lengths measure distances  (units)

Volumes measure an amount of space  (units)3

1 yd2 = 9 ft2

 

When converting areas, it all boils down to

If 1 yd = 3 feet,  then 12 yd2 = 32 ft2.

 

If 1 ft = 12 inches, the 12 ft2 = 122 inch2.   So that means there are 144 in2 = 1 ft2.  

 

If 1 m = 1000 mm then 12 m2 = 10002 mm2   = 1,000,000 mm2.

 

I could repeat this for volumes.

It all boils down to if

 

1 yd = 3 ft,

Then  13 yd3 = 33 ft3   1 yd3 =  27 ft3

 

If 1 inch = 2.54 cm,  then 13 inch3 = 2.543 cm3   or 1 inch3 = 16.3871 cm3

 

Homework on page 47 16 – 32 even.   And a quiz on the next 16 elements on Monday.